cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-3 of 3 results.

A258310 T(n,k) = 1/k! * Sum_{i=0..k} (-1)^(k-i) *C(k,i) * A258309(n,i); triangle T(n,k), n>=0, 0<=k<=floor(n/2), read by rows.

Original entry on oeis.org

1, 1, 2, 1, 4, 3, 9, 14, 3, 21, 50, 15, 51, 204, 122, 15, 127, 784, 644, 105, 323, 3212, 4115, 1310, 105, 835, 13068, 22587, 9270, 945, 2188, 55475, 137503, 85109, 16764, 945, 5798, 238073, 787127, 614779, 149754, 10395
Offset: 0

Views

Author

Alois P. Heinz, May 25 2015

Keywords

Examples

			Triangle T(n,k) begins:
:    1;
:    1;
:    2,     1;
:    4,     3;
:    9,    14,      3;
:   21,    50,     15;
:   51,   204,    122,    15;
:  127,   784,    644,   105;
:  323,  3212,   4115,  1310,   105;
:  835, 13068,  22587,  9270,   945;
: 2188, 55475, 137503, 85109, 16764, 945;
		

Crossrefs

Column k=0 gives A001006.
T(2n,n) gives A001147.
Row sums give A258311.

Programs

  • Maple
    b:= proc(x, y, t, k) option remember; `if`(y>x or y<0, 0,
          `if`(x=0, 1, b(x-1, y-1, false, k)*`if`(t, (k*x+y)/y, 1)
                      +b(x-1, y, false, k) +b(x-1, y+1, true, k)))
        end:
    A:= (n, k)-> b(n, 0, false, k):
    T:= proc(n, k) option remember;
           add(A(n, i)*(-1)^(k-i)*binomial(k, i), i=0..k)/k!
        end:
    seq(seq(T(n, k), k=0..n/2), n=0..14);
  • Mathematica
    b[x_, y_, t_, k_] := b[x, y, t, k] = If[y > x || y < 0, 0,
         If[x == 0, 1, b[x - 1, y - 1, False, k]*If[t, (k*x + y)/y, 1]
                     + b[x - 1, y, False, k] + b[x - 1, y + 1, True, k]]];
    A[n_, k_] := b[n, 0, False, k];
    T[n_, k_] := Sum[A[n, i] (-1)^(k - i) Binomial[k, i], {i, 0, k}]/k!;
    Table[Table[T[n, k], {k, 0, n/2}], {n, 0, 14}] // Flatten (* Jean-François Alcover, May 01 2022, after Alois P. Heinz *)

A258306 A(n,k) is the sum over all Motzkin paths of length n of products over all peaks p of (x_p+k*y_p)/y_p, where x_p and y_p are the coordinates of peak p; square array A(n,k), n>=0, k>=0, read by antidiagonals.

Original entry on oeis.org

1, 1, 1, 1, 1, 2, 1, 1, 3, 5, 1, 1, 4, 7, 14, 1, 1, 5, 9, 23, 43, 1, 1, 6, 11, 34, 71, 141, 1, 1, 7, 13, 47, 105, 255, 490, 1, 1, 8, 15, 62, 145, 411, 911, 1785, 1, 1, 9, 17, 79, 191, 615, 1496, 3535, 6789, 1, 1, 10, 19, 98, 243, 873, 2269, 6169, 13903, 26809
Offset: 0

Views

Author

Alois P. Heinz, May 25 2015

Keywords

Examples

			Square array A(n,k) begins:
:   1,   1,   1,   1,   1,    1,    1, ...
:   1,   1,   1,   1,   1,    1,    1, ...
:   2,   3,   4,   5,   6,    7,    8, ...
:   5,   7,   9,  11,  13,   15,   17, ...
:  14,  23,  34,  47,  62,   79,   98, ...
:  43,  71, 105, 145, 191,  243,  301, ...
: 141, 255, 411, 615, 873, 1191, 1575, ...
		

Crossrefs

Columns k=0-1 give: A258312, A140456(n+2).
Main diagonal gives A266386.

Programs

  • Maple
    b:= proc(x, y, t, k) option remember; `if`(y>x or y<0, 0,
          `if`(x=0, 1, b(x-1, y-1, false, k)*`if`(t, (x+k*y)/y, 1)
                      +b(x-1, y, false, k) +b(x-1, y+1, true, k)))
        end:
    A:= (n, k)-> b(n, 0, false, k):
    seq(seq(A(n, d-n), n=0..d), d=0..12);
  • Mathematica
    b[x_, y_, t_, k_] := b[x, y, t, k] = If[y > x || y < 0, 0, If[x == 0, 1, b[x - 1, y - 1, False, k]*If[t, (x + k*y)/y, 1] + b[x - 1, y, False, k] + b[x - 1, y + 1, True, k]]]; A[n_, k_] :=   b[n, 0, False, k]; Table[A[n, d - n], {d, 0, 12}, {n, 0, d}] // Flatten (* Jean-François Alcover, Jan 23 2017, translated from Maple *)

Formula

A(n,k) = Sum_{i=0..min(floor(n/2),k)} C(k,i) * i! * A258307(n,i).

A261785 Sum over all Motzkin paths of length n of products over all peaks p of (n*x_p+y_p)/y_p, where x_p and y_p are the coordinates of peak p.

Original entry on oeis.org

1, 1, 4, 13, 101, 571, 6735, 54713, 873019, 9274471, 187278048, 2460190261, 60205154959, 942541045811, 27121249048036, 492972449490417, 16312991079531595, 337650093459084079, 12633283010644517490, 293339323822142071021, 12245145846336974734339
Offset: 0

Views

Author

Alois P. Heinz, Aug 31 2015

Keywords

Crossrefs

Main diagonal of A258309.

Programs

  • Maple
    b:= proc(x, y, t, k) option remember; `if`(y>x or y<0, 0,
          `if`(x=0, 1, b(x-1, y-1, false, k)*`if`(t, (k*x+y)/y, 1)
                      +b(x-1, y, false, k) +b(x-1, y+1, true, k)))
        end:
    a:= n-> b(n, 0, false, n):
    seq(a(n), n=0..25);
  • Mathematica
    b[x_, y_, t_, k_] := b[x, y, t, k] = If[y > x || y < 0, 0, If[x == 0, 1, b[x - 1, y - 1, False, k]*If[t, (k*x + y)/y, 1] + b[x - 1, y, False, k] + b[x - 1, y + 1, True, k]]];
    a[n_] := b[n, 0, False, n];
    Table[a[n], {n, 0, 25}] (* Jean-François Alcover, Jun 10 2017, translated from Maple *)

Formula

a(n) = A258309(n,n).
Showing 1-3 of 3 results.